The present application relates to compositions and methods for depositing conductive metal and diffusion barrier compositions, and in particular, seed compositions and methods of using seed compositions for producing a layer of a conductive metal or diffusion barrier layer in a semiconductor or interlevel dielectric substrate.
As known in the art, conventional multilayer semiconductor structures generally include a semiconductor substrate (e.g., silicon, silicon carbide, or gallium arsenide) containing thereon at least one dielectric interconnect layer. Generally, the interconnect layer contains a dielectric material in which is embedded electrical components and circuitry (typically constructed of a conductive metal, e.g., copper). The dielectric layer is often referred to in the art as an interlayer or interlevel dielectric (ILD) or intermetal dielectric (IMD).
It is well known in the art that the dielectric is susceptible to metal migration. Therefore, it is common practice in the art for a metal barrier composition (e.g., Ta, TaN, or TiN) to be situated between the conductive circuit paths and the dielectric layer. Since copper is the most common conductive metal, the metal barrier composition typically functions to prevent copper diffusion; however, a variety of metal barrier compositions are available for functioning as a barrier to metals other than copper.
Metal barrier and conductive metal layers are typically deposited by such methods as CVD, PECVD, PVD, which often include a sputtering or plasma process. However, as linewidths narrow to well below one micron and into the nanometer region (e.g., less than 500 nm), these techniques are becoming less and less capable of maintaining the resolution required for such linewidths. Furthermore, although these deposition techniques are most suitable for depositing metal layers several microns thick, these deposition techniques are difficult to control and adjust in attempting to produce metal layers of only a few nanometers thick, as would be required for producing a layer having a thickness of only one, two, or a few atom layers.